[13u] 8234535: Cross compilation fails due to missing CFLAGS for the BUILD_CC

[Christoph Göttsches]

Hi,

I requested the backport of 8234535 to 13u and it has been approved. 
Since I don't have commit access, could someone please sponsor this 
changeset for me? The patch applies cleanly to the jdk13u-dev repository.

Bug: https://bugs.openjdk.java.net/browse/JDK-8234535
Original webrev: https://cr.openjdk.java.net/~cgo/8234535/webrev.01/
Commit: https://hg.openjdk.java.net/jdk/jdk/rev/eef0bf57357c

Thanks,
Christoph